A recent submission [1] to W3C, WS-Transfer [2], is a specification
for a
protocol that provides document retrieval and management â€” the same
service provided by HTTP. We infer that WS-Transfer is intended for
situations where:
* HTTP functionality is required but over some
message-passing system which does not support TCP
* There is a requirement for Web Services
capabilities, but no API is available to
access the HTTP protocol layer
* There is a requirement for some Web Service
capability that HTTP does not provide
The design of WS-Transfer raises a number of issues, several of which
are
mentioned in the W3C's staff comment on the submission [3]. These
issues
include:
* Does WS-Transfer's use of Web Services Addressing
End Point References (EPRs) instead of URIs
damage the Web?
* When WS-Transfer is carried over HTTP, can it make
proper use of HTTP as an application level-protocol?
Should a default HTTP binding be specified to promote
proper use of the WS-Transfer/SOAP/HTTP combination?
Some of these concerns were also discussed on the TAG's
teleconference of
10 October 2006 [4]. We note that the TAG has for some time been
tracking
at least two issues that are pertinent to WS-Transfer:
TAG issue whenToUseGet-7 [5] was originally raised in connection with
XML
Forms, but was also the umbrella under which GET support was integrated
into the SOAP Recommendation [6,7,8] and into its HTTP binding [9].
Those
changes provide means by which SOAP can properly use HTTP, and also
allow
for SOAP envelopes to be directly sourced from conventional Web servers
[10] such as Apache. The TAG also issued a related finding "URIs,
Addressability, and the use of HTTP GET and POST" [11]. The TAG has
reopened issue whenToUseGet-7, in part to facilitate discussion of
WS-Transfer.
Another issue pertinent to WS-Transfer is issue endPointRefs-47 [12],
under which the TAG has discussed several concerns relating to EPRs, and
their relationship to URIs. In October of 2005, the TAG requested [13]
changes to the Web Services Addressing draft Recommendations, to
indicate
the great value of using URIs, and only URIs, as the means of
identifying
resources.
In accepting the member submission of WS-Transfer, the W3C team
observed[3]:
"The W3C Team plans to notify the Web Services Coordination Group of
this
Member Submission but has no plans to start a Working Group in this
area.
The Team also plans to ask the Technical Architecture Group (TAG) to
investigate the impact of this technology on the architecture of the
Web."
Accordingly, this note is to announce that the TAG will indeed be
considering WS-Transfer, and to invite discussion on the www-tag@w3.org
mailing list.
Tim Berners-Lee
For the W3C Technical Architecture Group
[1] http://www.w3.org/Submission/2006/04/
[2] http://www.w3.org/Submission/WS-Transfer/
[3] http://www.w3.org/Submission/2006/04/Comment
[4]
http://lists.w3.org/Archives/Public/www-tag/2006Oct/att-0053/10-
tagmem-minutes.html
[5] http://www.w3.org/2001/tag/issues.html?type=1#whenToUseGet-7
[6] http://www.w3.org/TR/soap12-part2/#WebMethodFeature
[7] http://www.w3.org/TR/soap12-part2/#RPCResourceRetrieval
[8] http://www.w3.org/TR/soap12-part2/#soapresmep
[9] http://www.w3.org/TR/soap12-part2/#soapinhttp
[10] http://www.w3.org/TR/soap12-part2/#httpinterop
[11] http://www.w3.org/2001/tag/doc/whenToUseGet-20030922.html
[12] http://www.w3.org/2001/tag/issues.html?type=1#endPointRefs-47
[13] http://lists.w3.org/Archives/Public/www-tag/2005Oct/0057.html
ENDS